How to Safely Dispose of Storage Devices (SSD/HDD) and Prevent Data Leaks

When it comes to disposing of storage devices, many people know that it is not a good idea to throw them away as they are, because they may contain personal or confidential information. However, many do not actually know the proper way to dispose of them.

If a storage device is simply thrown away, or sold to a recycle shop or as a used item just to make a little money, there is a risk of information leakage, so this is not recommended.

If the proper disposal method is not known, data may leak from storage devices that end up on the secondhand market, increasing the risk of privacy invasion and information leaks.

Also, simply deleting files or formatting the storage does not completely erase the data, so it can be easily recovered using specialized tools.

This article explains how to safely erase data from storage devices, physical destruction methods, and how to use professional services for secure disposal.

Key Points of This Article

Disposing of storage with data left on it poses a risk of information leakage
Normal deletion or formatting does not completely erase data
Complete erasure requires data deletion tools
Physically destroying the storage is also effective
Using professional services allows for safe disposal
Recycle shops and secondhand sales carry a risk of information leakage
Data can be easily recovered using recovery tools
Physically destroying faulty storage is recommended

This article also explains basic knowledge about storage standards, mainstream storage configurations, and how to choose storage from the perspectives of performance and compatibility.

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How to Dispose of Storage Devices (SSD/HDD)

When disposing of storage devices, it is important to understand the necessity of data deletion, the risks in the secondhand market, and how easily data can be recovered.

How to Dispose of Storage Devices (SSD/HDD)

It is Necessary to Completely Delete Data
Risk of Data Leakage in the Secondhand Market
Data Can Be Easily Recovered

It is Necessary to Completely Delete Data

If storage is disposed of as is, there is a risk that personal or confidential information may leak, so it is necessary to completely delete the data before disposal.

However, simply “deleting files normally” or formatting does not completely erase the data.

“Normal file deletion” refers to the following actions:

Selecting a file and deleting it by right-clicking or pressing the Delete key
Right-clicking the Recycle Bin and selecting “Empty Recycle Bin”
Deleting data inside the Recycle Bin (permanent deletion)
Deleting while holding Shift for permanent deletion

However, with normal file deletion, the area on the storage where the file was stored is marked as “free space,” but the data itself remains on the storage.

In reality, data is only truly deleted from storage when new data is written to the same physical area as the deleted file.

Until new data is written, Windows treats the file as if it does not exist, and users cannot see the file (it appears deleted).

Therefore, data can be easily recovered using recovery tools and similar software.

For those who want to know more about why data remains on storage even after deletion, please refer to the following article.

Because of these storage specifications, it is necessary to dispose of storage in a way that completely deletes or makes the data unreadable, such as:

Using dedicated data erasure tools
Physically destroying the storage
Requesting a professional service

Each method will be explained later, so choose the disposal method that suits your needs.

Never dispose of storage with only normal file deletion, or without even deleting files at all.

Risk of Data Leakage in the Secondhand Market

If storage is sold to a recycle shop or secondhand shop without proper data deletion, there is a risk that personal or confidential information may be passed on to third parties.

In fact, there have been reports on X (formerly Twitter) and YouTube videos showing data being found on storage purchased from secondhand shops.

Sometimes, users did not delete their data before selling, and in other cases, data was recovered using recovery software.

In some videos, photos of the previous owner (with mosaic applied in the video) were actually found, so selling storage to secondhand shops without proper measures is very risky.

Also, if a storage device is given to an untrustworthy company for disposal, there is a chance that the company may resell the storage in the secondhand market.

If the collected storage is not disposed of and is instead resold as a used item, there is a high risk that personal or confidential information will end up in the hands of third parties.

Ken

Of course, only a small number of companies do such things!

Therefore, it is necessary to use safe methods such as reliable companies, services that physically destroy the storage in front of the customer, or services that issue a certificate of data erasure.

Data Can Be Easily Recovered

Isn’t data recovery something that only people with advanced skills can do, so as long as the files are deleted and not visible, there isn’t much risk?

It is absolutely not acceptable to sell storage without even deleting files, but some may think, “Only people who are good with computers can recover data…”

That is not the case at all. Anyone can easily recover data using recovery tools.

Specific methods are introduced in the following articles, so details are omitted here.

In fact, I have used such tools myself, and if there are only a few files, they can be recovered in just a few minutes.

All it takes is selecting the target storage and the files to recover, then pressing the recovery button, so anyone can do it without special skills.

If you want to see the actual operation with images, check out the review article on the recovery software ‘Recoverit’.

How to Dispose of Storage Devices (SSD/HDD)

This section explains how to safely erase data from storage devices.

How to Dispose of Storage Devices (SSD/HDD)

It is Necessary to Completely Delete Data
Risk of Data Leakage in the Secondhand Market
Data Can Be Easily Recovered

Using Data Deletion Tools

Data deletion tools are software designed to completely erase data from storage devices (SSD / HDD / USB memory, etc.).

With normal deletion or formatting, data is not completely erased and can potentially be recovered using recovery software. However, by using data deletion tools, data is rendered unrecoverable, preventing the risk of information leakage.

Data deletion tools overwrite the data area multiple times with meaningless data (such as zeros or random bit patterns).

This makes the original data undetectable both magnetically and electrically.

The patterns and number of overwrites are specified by data erasure standards.

Data erasure standards are guidelines and criteria established to safely erase digital data.

These standards specify erasure methods, procedures, and the required number of overwrites, aiming to minimize the risk of data recovery.

To prevent leaks of confidential or personal information, standards set by government agencies and industry bodies in various countries are widely used.

There are various data deletion standards, such as the U.S. Department of Defense’s ‘DoD 5220.22-M’, which overwrites data three times (once with 0, once with 1, and once with random data), and the very strict ‘Gutmann method’, which overwrites data 35 times.

If data is overwritten only once, it may be possible to recover previous data from weak residual magnetism using special equipment on HDDs.

For SSDs, a technology called “wear leveling” is used to extend lifespan by writing data evenly to different cells in the flash memory.

Because of this, overwriting only once may leave data in other cells, and data that has not been deleted may remain in spare areas.

Different tools support different data erasure standards, but for these reasons, data is completely erased based on standards that require multiple overwrites.

I used to work for a security software company, and we would use these data erasure standards to delete storage data, which could take two to three hours.

Ken

I had to delete data every time I changed computers when switching teams!

Recommended data deletion tools include:

Physically Destroying the Storage

Another method is to physically destroy the storage device.

Specific methods include drilling holes in the storage or smashing it with a hammer.

These methods physically damage the recording surface of the storage, making the data unreadable.

However, when physically destroying storage, it is important to take safety precautions and use appropriate protective gear.

It can be difficult to do this yourself, as metal or glass fragments may scatter, so it is a good idea to use a service that offers physical destruction.

Bic Camera (Stores: Nationwide)
PC Comfull (Stores: Akihabara, Namba, Nagoya, Umeda, Kobe Sannomiya)
Akihabara Final Disposal Site

It is unclear whether all Bic Camera stores offer this service, so inquire in advance if necessary.

By physically destroying the storage, it cannot be connected to a computer and recognized, so it cannot be easily recovered using data recovery tools.

However, if there are large fragments and someone with special equipment and high technical skills, it may be possible to recover data, but for personal use rather than handling corporate confidential information, this should not be a problem.

If you are concerned, use data deletion tools in combination for extra security.

Also, if the storage is already faulty and not recognized by the computer, data deletion tools cannot be used, so physical destruction is effective.

That said, if the computer cannot recognize the storage, data recovery tools cannot recover the data, so whether to physically destroy it depends on how much security you want.

Using Professional Services

Professional storage disposal companies have specialized technology and equipment for data erasure and physical destruction, ensuring that data is completely unrecoverable.

Some companies also issue a disposal certificate, confirming that the data has been properly disposed of.

The benefits of having a disposal certificate include:

Proof of Data Deletion
The certificate proves that the storage device requested for disposal has had its data completely deleted using proper methods. This objectively shows that the requester has taken the necessary steps to prevent data leaks.
Compliance with Laws and Regulations
Especially for companies and organizations, proper data disposal is required to comply with the Personal Information Protection Law and information security regulations. With a certificate, it can be confirmed that data deletion was performed in accordance with the law, and if problems arise later, it can be shown that measures were taken.
Reassurance for Customers and Business Partners
When companies or organizations delete data, presenting a certificate can assure customers and business partners that there is no risk of information leakage, increasing trust.
Support for Audits and Internal Checks
Having a certificate makes it easier to respond to internal and external security audits. Being able to prove the deletion process helps prevent trouble in advance.

Especially for companies and organizations, it is recommended to use professional services from the perspective of legal compliance and security policies.

Professional storage disposal companies include:

Check the types of storage supported, whether certificates are issued, fees, and procedures to choose the service that best suits your needs.

Summary: Dispose of Storage So It Cannot Be Recovered!

This article explained the importance of complete data deletion and the risks of information leakage when disposing of storage, and introduced three disposal methods.

Here is a summary of the key points:

Key Points of This Article

Disposing of storage with data left on it poses a risk of information leakage
Normal deletion or formatting does not completely erase data
Complete erasure requires data deletion tools
Physically destroying the storage is also effective
Using professional services allows for safe disposal
Recycle shops and secondhand sales carry a risk of information leakage
Data can be easily recovered using recovery tools
Physically destroying faulty storage is recommended

When disposing of storage, it is important to ensure that data cannot be recovered, from the perspective of preventing information leakage.

Instead of normal file deletion, which leaves data on the storage, use tools to completely erase the data or physically destroy the storage so it cannot be read.

Also, by using professional services, storage can be disposed of more safely and securely.

Choose the method that best suits your data, effort, and budget to safely dispose of your storage.

This article also explains basic knowledge about storage standards, mainstream storage configurations, and how to choose storage from the perspectives of performance and compatibility.